Saliency based beam-forming for object detection

ABSTRACT

A scanning device generally produces an image having a uniform resolution throughout a target region. To improve radar scanning/lidar scanning, an efficient scan approach to enable a radar device/lidar device to adoptively perform a scan of a target region based on interested regions and/or an adjustable resolution. The apparatus may be a scanning device for scanning. The apparatus performs a first scan over a target region to obtain a plurality of first scan samples at a plurality of locations within the target region. The apparatus generates a saliency map of the target region based on signal intensities of the plurality of first scan samples. The apparatus determines a salient region within the target region based on the saliency map. The apparatus performs at least one second scan over the salient region to obtain at least one second scan sample in the salient region.

BACKGROUND Field

The present disclosure relates generally to object detection systems,and more particularly, to object detection by a scanning device forradio-based scanning or laser-based scanning.

Background

Object detection techniques have been developed for various applicationsincluding autonomous cars, drones and mobile robots. The objectdetection techniques may use different sensors and be employed invarious devices based on object detection range and environmentalconditions. For example, to enable a vehicle to detect an object in anarea surrounding the vehicle, various sensors such as optical sensors,acoustic sensors, and laser-based sensors have been employed invehicles. Object detection techniques using a radio-based scanningsensor such as a radar sensor or a laser-based scanning sensor such as alight detection and ranging (lidar) sensor have also been used. Lidarscanning generally provides a high resolution, but a distance over whichan object can be reliably detected by lidar-based scanning may be short.Radar scanning of a scene or area may not be affected by environmentalconditions such as weather as much as scanning approaches using othertypes of sensors. Further, a radar sensor scan may have a longer rangethan other types of sensors, and thus allow a scan over a longerdistance. However, a radar sensor scan may be limited by processingpower of an associated scanning device. The limited processing power mayresult in low scan resolution, longer scan processing time, etc.Therefore, a scanning approach using radar scanning and/or lidarscanning that provides efficient scanning and improved object detectionis desired.

SUMMARY

The following presents a simplified summary of one or more aspects inorder to provide a basic understanding of such aspects. This summary isnot an extensive overview of all contemplated aspects, and is intendedto neither identify key or critical elements of all aspects nordelineate the scope of any or all aspects. Its sole purpose is topresent some concepts of one or more aspects in a simplified form as aprelude to the more detailed description that is presented later.

A scanning device (e.g., a radar device or a lidar device) scans atarget region to detect an object and generally produces data or animage having a uniform resolution throughout the target region for eachscan. Hence, the scanning device generally lacks a feature to adjust aresolution in a certain portion within the target region and also lacksa feature to focus a scan in interested regions. Therefore, an efficientscan approach to enable a radar device/lidar device to adoptivelyperform a scan of a target region based on interested regions and/or anadjustable resolution.

In an aspect of the disclosure, a method, a computer-readable medium,and an apparatus are provided. The apparatus may be a scanning devicefor scanning. The apparatus performs a first scan over a target regionto obtain a plurality of first scan samples at a plurality of locationswithin the target region. The apparatus generates a saliency map of thetarget region based on signal intensities of the plurality of first scansamples. The apparatus determines a salient region within the targetregion based on the saliency map. The apparatus performs at least onesecond scan over the salient region to obtain at least one second scansample in the salient region.

To the accomplishment of the foregoing and related ends, the one or moreaspects comprise the features hereinafter fully described andparticularly pointed out in the claims. The following description andthe annexed drawings set forth in detail certain illustrative featuresof the one or more aspects. These features are indicative, however, ofbut a few of the various ways in which the principles of various aspectsmay be employed, and this description is intended to include all suchaspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example diagram illustrating an example use of a radarsensor/lidar sensor to detect an object.

FIG. 2 is an example diagram of a digital beam-forming circuit for aradar device/lidar device.

FIGS. 3A and 3B are example diagrams illustrating steering of a mainlobe of a receiver antenna array.

FIG. 4 is an example diagram illustrating a complex multiplier used toapply a complex weight component to a received wave signal.

FIG. 5 is an example diagram illustrating a beamforming system for areceiver antenna array.

FIG. 6 is an example diagram illustrating a radar device/lidar deviceperforming a scan of a region.

FIG. 7 is an example diagram illustrating radar/lidar scans according toan aspect of the disclosure.

FIG. 8 is an example diagram illustrating a first approach using fastscanning according to an aspect of the disclosure.

FIG. 9 is an example diagram illustrating a second approach using highresolution scanning according to an aspect of the disclosure.

FIG. 10 is a flowchart of a method of scanning by a scanning device,according to an aspect of the disclosure.

FIG. 11 is a flowchart of a method of scanning by a scanning device,expanding from the flowchart of FIG. 10.

FIG. 12 is a conceptual data flow diagram illustrating the data flowbetween different means/components in an exemplary apparatus.

FIG. 13 is a diagram illustrating an example of a hardwareimplementation for an apparatus employing a processing system.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of various configurations and isnot intended to represent the only configurations in which the conceptsdescribed herein may be practiced. The detailed description includesspecific details for the purpose of providing a thorough understandingof various concepts. However, it will be apparent to those skilled inthe art that these concepts may be practiced without these specificdetails. In some instances, well known structures and components areshown in block diagram form in order to avoid obscuring such concepts.

Several aspects of telecommunication systems will now be presented withreference to various apparatus and methods. These apparatus and methodswill be described in the following detailed description and illustratedin the accompanying drawings by various blocks, components, circuits,processes, algorithms, etc. (collectively referred to as “elements”).These elements may be implemented using electronic hardware, computersoftware, or any combination thereof. Whether such elements areimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or anycombination of elements may be implemented as a “processing system” thatincludes one or more processors. Examples of processors includemicroprocessors, microcontrollers, graphics processing units (GPUs),central processing units (CPUs), application processors, digital signalprocessors (DSPs), reduced instruction set computing (RISC) processors,systems on a chip (SoC), baseband processors, field programmable gatearrays (FPGAs), programmable logic devices (PLDs), state machines, gatedlogic, discrete hardware circuits, and other suitable hardwareconfigured to perform the various functionality described throughoutthis disclosure. One or more processors in the processing system mayexecute software. Software shall be construed broadly to meaninstructions, instruction sets, code, code segments, program code,programs, subprograms, software components, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise.

Accordingly, in one or more example embodiments, the functions describedmay be implemented in hardware, software, or any combination thereof. Ifimplemented in software, the functions may be stored on or encoded asone or more instructions or code on a computer-readable medium.Computer-readable media includes computer storage media. Storage mediamay be any available media that can be accessed by a computer. By way ofexample, and not limitation, such computer-readable media can comprise arandom-access memory (RAM), a read-only memory (ROM), an electricallyerasable programmable ROM (EEPROM), optical disk storage, magnetic diskstorage, other magnetic storage devices, combinations of theaforementioned types of computer-readable media, or any other mediumthat can be used to store computer executable code in the form ofinstructions or data structures that can be accessed by a computer.

Various types of sensors have been developed to detect objects. Forexample, one or more types of sensors may be implemented in a vehicle tohelp the vehicle detect an object. Each type of sensor may haveadvantages and disadvantages. For example, advantages of optical sensorssuch as a camera or a lidar (light detection and ranging) device mayinclude that the size of an optical sensor is small, the sensorresolution may be made high, and that algorithms for object recognition,motion detection, etc. have been developed. Disadvantages of opticalsensors may include a limited distance over which an object may bedetected (or sensed). For example, a focal length in a camera sensorand/or a return power for a lidar sensor may limit the distance (e.g.,up to 100 meters) that the optical sensors can detect/distinguishobjects.

Radar sensors may be used for object detection. An advantage of theradar sensor is that the radar sensor may be capable of reliably sensing(and detecting an object) at a longer distance than optical sensors. Forexample, a radar sensor device may be able to reliably detect an objectthat is more than 200 meters away from the radar sensor device. Forexample, detection of an object may be considered reliable when theobject detected by the radar sensor device can be distinguished from asurrounding environment or another object. The long distance sensing ofa radar sensor may be an important feature especially when employed in avehicle that may move at a high rate of speed (e.g., at highway speeds).Warning of a possible collision should be provided to a driver of thevehicle to enable sufficient time for the driver to react, and thus thelong distance sensing may provide the driver with the sufficient time toreact. Another advantage of radar is that the radar may be capable ofsensing objects in environmental conditions where optical sensors orother types of sensors have difficulty sensing an object due to theenvironmental conditions. For example, unlike optical sensors, radarsensors may detect objects in snow or rain or fog.

FIG. 1 is an example diagram 100 illustrating an example use ofradar/lidar sensing to detect an object. The scanning device 112 maysense an object 122. In an aspect, the scanning device 112 may include aradar scanning device to sense the object 122 by sensing radio wavessignals (or microwave signals) that are reflected from the object 122.In particular, the radar scanning device included in the scanning device112 may transmit radio waves (or microwaves) at 132. When the radarradio waves reach the object 122, the radio waves are reflected by theobject 122. Then the radar scanning device included in the scanningdevice 112 may receive at 134 the reflected radio waves to sense theobject 122. In an aspect, the scanning device 112 may include a lidarscanning device to sense the object 122 by laser scanning. The scanningdevice 112 may be implemented in a vehicle 110 or may be implemented ina stationary structure, for example.

The radar may lack high angular resolution, due to a wide beam width.For example, a radar device may not be able to distinguish two separateobjects that are less than 5° apart. The lack of angular resolution ofthe radar may prevent the radar from providing reliable sensingespecially over a short distance. Beamforming may be employed toincrease the angular resolution of the radar. Beamforming is a techniquethat may achieve high angular accuracy and increased resolution by usingan array of multiple radar antenna elements. However, increasing theangular resolution may increase the size of the sensor array such thatthe size of the sensor array to achieve sub-1° resolution may be large.A radar device using existing beamforming techniques may scan a regionin a uniform fashion, generally by sensing radar return signals atequally spaced locations over the region, without differentiatingbetween an interesting zone in the region, e.g., a zone with a detectedobject, and other zones in the region. Thus, there is a need forlow-cost, small form-factor radar sensors that have increased accuracyand increased resolution by taking advantage of the information in theradar returns, e.g., by using beamforming to focus the radar scan oninteresting zones to speed up the radar scan and/or to increase theresolution on the interesting zones to distinguish objects that areclose together and would appear as a single object when scanned at alower resolution to cover the entire region. The similar beamformingtechnique may also be applied to a lidar device.

In a radar device or a lidar device, several non-directional antennaelements in a receiver antenna array may be used to scan a target region(e.g., in front of the receiver antenna array). The receiver antennaelements receive wave signals, and output the received wave signals. Theoutput from each of the antenna elements may pass into a processor(e.g., digital signal processor (DSP)) via an analog-to-digital (A/D)converter. The DSP aggregates the output from each antenna element in away that simulates a large single antenna, by effectively “steering” thereceiver antenna array, using a beamforming approach. In particular,phase delays may be applied to the receiver antenna elements, such thatwhen the phase-delayed signals from the receiver antenna elements areadded together, the effect of digital steering of the receiver antennaarray is achieved. Thus, the steering of the receiver antenna array isperformed digitally by varying the phase values of the individualantenna elements. By varying the phase values of the individual receiverantenna elements, the radar device or the lidar device may digitallysteer a main lobe of the receiver antenna array to a desired direction.The receiver antenna array has a maximum gain at a direction of the mainlobe, and thus the direction of the main lobe is effectively a scanningdirection. Alternatively, steering of the receiver antenna array may beperformed by mechanically steering the receiver antenna array elementssuch that a main lobe of the receiver antenna array will be placed in aspecific direction. By mechanically steering the receiver antenna arrayelements, the aggregated receiver antenna elements become physicallybiased to have the main lobe pointing in the specific direction. Thatis, the antenna gain has a maximum receive gain along the specificdirection.

FIG. 2 is an example diagram 200 of a digital beam-forming circuit for aradar device/lidar device. The signal generator 210 generates a wavesignal (e.g., radiofrequency signal), which is forwarded by a controller212 to a wave transmitter 214. The transmitted signals may be reflectedby an obstruction (e.g., an object, a structure, etc.). The receiverantenna array 220 includes antenna array elements 222-1, 222-2, . . . ,222-n that are configured to receive the reflected signals. Thecontroller 212 applies respective phase delays to the received signalsat the weighting modules 232-1, 232-2, . . . , 232-n. The weightedsignals from the weighting modules 232-1, 232-2, . . . , 232-n areamplified by the amplifiers 242-1, 242-2, . . . , 242-n, and are passedthrough analog-digital converters 252-1, 252-2, . . . , 252-n,respectively. The DSP 262 collects the resulting signals and processesthe resulting signals to produce a composite scan.

FIGS. 3A and 3B are diagrams illustrating steering of a main lobe of areceiver antenna array. For illustration purposes, in FIGS. 3A and 3B,the receiver antenna array physically faces a 90 degree angle. FIG. 3Ais an example diagram 300 where no phase delay is applied to receiverantenna elements. Because no phase delay is applied, a main lobe 310stays at a 90 degree angle, without being steered to another direction.Thus, in FIG. 3A, the receiver antenna array in FIG. 3A receives signalsat the 90 degree angle, and thus has a maximum receive gain along the 90degree angle. FIG. 3B is an example diagram 350 where phase delays areapplied to receiver antenna elements. In the example of FIG. 3B, thephase delays are applied such that a main lobe 360 of the receiverantenna array is digitally steered to the left, at 135 degrees. Thus, inFIG. 3B, the receiver antenna array in FIG. 3G receives wave signals atthe 135 degree angle, and thus has a maximum gain at the 135 degreeangle.

A phase delay can be applied to a receiver antenna element by adding acomplex weight that includes an amplitude component and a phasecomponent. The phase component is used to add a delay, and the amplituderepresents a gain. FIG. 4 is an example diagram 400 illustrating acomplex multiplier used to apply a complex weight component to areceived wave signal. For example, the controller 212 and the weightingmodules 232-236 of FIG. 2 may have the complex multiplier features. Theoutput from each receiver antenna element is multiplied by a complexweight component w that specifies how much to weigh the amplitude(a_(k)) and how much to rotate the phase (θ_(k)). The complex weight canthus be expressed as w_(k)=a_(k) e^(j sin(θk)). The weights may beapplied on all of the elements to get an effective gain and an effectivedirection based on the weights. In the diagram 400 of FIG. 4, thecomplex baseband signal from k^(th) receiver antenna element is splitinto an in-phase portion i_(k) and a quadrature portion q_(k), and thein-phase portion i_(k) and the quadrature portion q_(k) are weighted bythe complex weight w_(k), which results a real part of the weightedsignal s_(k)(t)w_(k) and an imaginary part of the weighted signals_(k)(t)w_(k). By adjusting the weights, the array may be pointed in aparticular direction with a particular gain.

FIG. 5 is an example diagram 500 illustrating a beamforming system for areceiver antenna array. In the example diagram 500, a receiver antennaarray 510 has four antenna elements, although more or fewer antennaelements may be used. The antenna elements of the receiver antenna array510 receive signals and forward the signals to RF translators 520,respectively. A shared local oscillator may input a signal to each ofthe RF translators 520. The outputs of the RF translators 520 are inputto respective A/D converters 540. A shared sampling clock 552 may inputa square wave signal to each of the A/D converters 540 to convert theanalog signal to a digital signal. The outputs of the A/D converters 540are input to a DSP 570, and may be forwarded to other beamformers. TheDSP 570 includes digital down-converters 572, weighting modules 574, anda summation module 576. In particular, the outputs of the A/D converters540 are forwarded to the digital down-converters 572 that respectivelyproduce baseband signals (s₁(t), s₂(t), s₃(t), s₄(t)). The weightingmodules 574 respectively bias the baseband signals (s₁(t), s₂(t), s₃(t),s₄(t)), with respective weights (w₁, w₂, w₃, w₄). The resulting weightedsignals (s₁(t)w₁, s₂(t)w₂, s₃(t)w₃, s₄(t)w₄) are aggregated by thesummation module 576 to generate a beam-formed complex baseband signals(t)w, which is output to a demodulator.

Radar devices/lidar devices (e.g., a radar device or a lidar device forautomotive cases) may scan an environment by beamforming receivedsignals from the receiver antenna array, thereby sampling for potentialobject detection in the paths of transmitted beams over several scaniterations. For each scan iteration, the radar device/lidar devicesteers the beam of the receiver antenna array in a particular directionsuch that completion of all scan iterations results in a single scan ofthe environment, where a single scan includes data from each directionthe beam is steered. As discussed above, the received signals at thereceiver antenna array may be reflected signals of a transmitted beam(e.g., radio frequency signal). When a radar device/lidar deviceperforms a scan, the radar device/lidar device may steer the beam of thereceiver antenna array (e.g., by beamforming) to equally-spacedlocations on a target region over multiple scan iterations, where eachscan iteration involves the receiver antenna array receiving a signalfrom a corresponding location on a target region. Thus, a radardevice/lidar device may produce data or an image having a uniformresolution over the target region. For example, a radar device/lidardevice may utilize all available receiver antenna elements to obtain thehighest possible resolution for each scan iteration over a targetregion.

FIG. 6 is an example diagram 600 illustrating a radar device/lidardevice performing a scan of a region. A scanning device 650 having areceiver antenna array with multiple antenna elements performs a scan ofa target region 610, where the scanning device may include a radardevice and/or a lidar device. The scanning device 650 performs the scanby receiving signals reflected from various portions of the targetregion 610. The scanning device 650 may steer the beam (e.g., bybeamforming) to directions corresponding to these portions of the targetregion 610 to receive signals from these portions. In the examplediagram 600, the scanning device 650 performs the scan by receivingsignals at 50 (5×10) different portions in the target region 610, thussampling at 50 scan iterations per scan. Each time the scanning device650 steers the beam to a different direction, the scanning device 650obtains signals (radar/lidar returns). In this example, the scanningdevice 650 steers the beam to 50 (5×10) different directions such thatthe scanning device 650 may receive signals (radar/lidar returns) fromthe 50 (5×10) different directions. The first scan result 660 shows 50circles representing radar/lidar signal returns at 50 different scanangles (directions). The number of circles (scan iterations) per scan isgenerally limited by the processing power of the scanning device (e.g.,processing power of the DSP) because each scan iteration consumesprocessing power. In the first scan result 660, black circles illustratelow intensity or no intensity and shaded circles illustrate highintensity indicating signal reflection from an object. The shadedcircles correspond to the two objects (a ball and a person) in thetarget region 610. Because the signals are reflected from the twoobjects in the target region 610, the corresponding regions observe highintensity as illustrated by the shaded circles.

Because a radar device/lidar device may produce data or an image havinga uniform resolution throughout a target region for each scan, the radardevice/lidar device may lack a feature to adjust the resolution in acertain direction or in a certain location adaptively based onsurrounding conditions (e.g., based on initial scan information).Further, a radar device/lidar device may utilize all available receiverantenna elements to scan each location to reduce the beam-width of themain lobe for higher resolution. However, utilizing all availablereceiver antenna resources for all scan iterations may be time consumingand may consume processing power. Further, reallocation of the receiverantenna resources to achieve increased accuracy in zones of the regionby adaptively adjusting the resolution and/or the number of scaniterations utilized in scanning may be desirable.

According to an aspect of the disclosure, a radar device/lidar deviceadaptively determines resource allocations regarding the receiverantenna elements based on one or more previous radar/lidar scans. Theaspect may provide increased efficiency and/or increased accuracy ofobject tracking for a given number of receiver antenna elements (M), ascan frequency (F Hz), and a number of directions per scan (D). Inparticular, before making a decision to utilize a specific amount ofantenna resources to perform a scan, a radar device/lidar device (e.g.,a DSP of the radar device/lidar device) performs one or more initialscans to determine a statistical significance (e.g., probability) onwhether an object is present at a particular angle or not. In an aspect,if the radar device/lidar device determines based on the initial scansthat an object is present at the particular angle, the radardevice/lidar device may adjust the resource allocations. For example, ifa radar device/lidar device scans 20 times per target region and isinitially configured to collect 50 samples (50 scan iterations) indifferent directions, the radar device/lidar device performs a firstscan (e.g., an initial scan) using receiver antenna arrays to collectall 50 samples. The 50 samples may be equally spaced from one another.Then, the radar device/lidar device creates a saliency map using thereceived signals (radar/lidar returns) of the first scan. Based on thesaliency map, the radar device/lidar device may perform a subsequentscan by scanning only portions within the target region that previouslygenerated higher intensity of received signals. Hence, instead ofscanning every single angle in a region, the radar device/lidar devicemay reallocate antenna resources to focus on interested regions (e.g.,regions with higher intensity/objects). Therefore, in one aspect, afterthe first scan, the radar device/lidar device may collect less than 50samples per scan, based on the saliency map. In an aspect, after thefirst scan, the radar device/lidar device may increase the resolutionfor the receiver antenna array to focus on the interested regions.

FIG. 7 is an example diagram 700 illustrating radar/lidar scansaccording to an aspect of the disclosure. In the example diagram 700 ofFIG. 7, a radar device/lidar device is initially configured to steer thebeam to receive signals in D different directions (D scan iterations). Dmay be 64. Thus, during the first scan, the radar device/lidar devicereceives signals (radar/lidar returns) in D different directions usingthe receiver antenna array. Based on the first scan, the radardevice/lidar device analyzes the radar/lidar returns and generates asaliency map based on intensity (e.g., signal strength) of the receivedsignals. For example, the saliency map may represent portion(s) in thetarget region that have high intensity (e.g., intensity higher than anintensity threshold). The radar device/lidar device may map the saliencymap to weights (e.g., complex weights) to apply to respective receiverantenna elements to steer the beam of the receiver antenna array basedon the saliency map. In particular, the beam of the receiver antennaarray may be steered to directions corresponding to high intensityportions in the saliency map. During the second scan, the radardevice/lidar device receives signals (radar/lidar returns) in ddifferent directions, where d is an integer, based on the saliency map.Similarly, for each of the rest of the scans, the radar device/lidardevice receives signals (radar/lidar returns) in d different directionsbased on the saliency map. In one aspect, d may be less than D, and thusthe radar device/lidar device may receive signals in less than Ddifferent directions, due to the saliency map. In an aspect, the radardevice/lidar device may perform a reset scan after several scans usingthe saliency map, where the reset scan is performed without using thesaliency map. For example, because the objects in the target region maychange, a reset scan may be performed to generate a new saliency mapwith salient regions from time to time. In one example, the radardevice/lidar device in a vehicle may be in motion, and thus the targetregion may change as the radar device/lidar device moves, thus changingobjects within the target region. In another example, even if the radardevice/lidar device is stationary, objects in the target region maymove, and thus locations and/or presence of the objects in the targetregion may change. These examples show that updating the saliency map byperforming a reset scan may be beneficial. Thus, the reset scan may befor the purpose of dead reckoning. The radar device/lidar device maygenerate a new saliency map with salient regions based on the resetscan, and then perform subsequent scans based on the new saliency mapand the salient regions.

When the radar device/lidar device performs a subsequent scan based on asaliency map, at least one of two approaches may be implemented for theradar device/lidar device to perform the subsequent scan. According to afirst approach, the radar device/lidar device maintains a number ofdifferent directions (scan iterations) that fall within the saliency mapto receive signals. That is, the radar device/lidar device maintains theresolution for a zone in the region identified by the saliency map.Because the saliency map may indicate a smaller zone of interest thanthe target region, the radar device/lidar device may take less time toperform a scan of the zone if a number of different directions that fallwithin the zone is unchanged. Therefore, the first approach may becalled a fast scan approach.

FIG. 8 is an example diagram 800 illustrating a first approach usingfast scanning according to an aspect of the disclosure. In the examplediagram 800 of FIG. 8, a target region 810 is a scene with two objects,a ball 812 and a person 814. In this example, the radar device/lidardevice is initially configured to receive signals at 50 (5×10) differentdirections (50 scan iterations) per scan. Thus, when the radardevice/lidar device performs a first scan of the target region 810, theradar/lidar return 830 includes signal intensities at 50 differentdirections within the target region 810. As a result of the first scan,the radar device/lidar device obtains the radar/lidar return 830 showingdetected objects as shaded circles and the surrounding regions as blackcircles, where the shaded circles represent directions where thereceived signals have high intensity (e.g., greater than an intensitythreshold) indicating reflection from an object, and the black circlesrepresent directions where the received signals have low intensity(e.g., less than the intensity threshold). After the first scan, theradar device/lidar device generates a saliency map. The saliency map hasa first salient region 852 and a second salient region 854. The firstsalient region 852 is generated based on the 4 shaded circlescorresponding to the signals reflected from the ball 812, and the secondsalient region 854 is generated based on the 8 shaded circlescorresponding to the signals reflected from the person 814. Thus, thesaliency map 850 may identify 12 different directions, including 4directions of the 4 shaded circles corresponding to the ball 812 and 8directions of the 8 shaded circles corresponding to the person 814 ofinterest.

After the saliency map 850 is generated, the radar device/lidar deviceis configured to receive signals at directions corresponding to thesaliency map 850. Thus, in this example, the radar device/lidar deviceis configured to receive signals at 4 different directions in the firstsalient region 852 and at 8 different directions in the second salientregion 854. Therefore, in a next scan 870, the radar device/lidar deviceobtains signal intensities for signals received at 12 differentdirections (scan iterations), which include 4 different directions inthe first salient region 852 and at 8 different directions in the secondsalient region 854. As illustrated, a number of scan iterations per areawithin the saliency map 850 in the next scan 870 is the same as a numberof scan iterations per area in the first scan 830. Because the radardevice/lidar device receives signals in less directions (fewer scaniterations) during the next scan than during the first scan, the radardevice/lidar device takes less time to perform the next scan than toperform the first scan. After several scans based on the saliency map850, the radar device/lidar device may perform a reset scan(“dead-reckon”) without using the saliency map 850. The radardevice/lidar device may generate a new saliency map based on the resetscan, and then perform subsequent scans based on the new saliency map.The radar device/lidar device may perform the reset scan every w scans,where w is an integer.

According to a second approach, the radar device/lidar device mayincrease a number of different directions (scan iterations) that fallwithin a saliency map to receive signals. That is, the radardevice/lidar device may increase the resolution of a region within thesaliency map. In an aspect, when increasing the resolution of a region,an angular resolution of the receiver antenna array may be considered.An angular resolution is minimum angular separation at which two equaltargets can be separated when at the same range. The number of differentdirections (scan iterations) may be increased to a number where theangular resolution is high enough to distinguish two adjacentdirections. The radar device/lidar device may increase an angularresolution by increasing a number of receiver antenna elements used toreceive a signal. In particular, increasing a number of receiver antennaelements may decrease the beam width of the receive antenna array, whichresults higher angular resolution. With the narrower beam width, theradar device/lidar device may be able to increase a number of differentdirections (scan iterations) more effectively. In an aspect, a higherradar/lidar scan frequency may provide higher angular resolution. Thus,the angular resolution of the receiver antenna array may be affected bythe number of receiver antenna array elements and the radar/lidar scanfrequency. Because the radar device/lidar device scans the regioncorresponding to the saliency map with the increased resolution,processing time and processing power may be reduced as compared toscanning the entire target region with the increased resolution. Thesecond approach may be called a high resolution scan approach.

FIG. 9 is an example diagram 900 illustrating a second approach usinghigh resolution scanning according to an aspect of the disclosure. Inthe example diagram 900 of FIG. 9, a target region 910 is a scene withtwo objects, a ball 912 and a person 914. The radar device/lidar deviceis initially configured to receive signals at 50 (5×10) differentdirections (50 scan iterations) per scan. The 50 directions may beequally spaced. Thus, when the radar device/lidar device performs afirst scan of the target region 910, the radar/lidar return 930 includessignal intensities at 50 different directions within the target region910. As a result of the first scan, the radar device/lidar deviceobtains the radar/lidar return 930 showing detected objects as shadedcircles and the surrounding regions as black circles, where the shadedcircles represent directions where the received signals have highintensity (e.g., greater than an intensity threshold) indicatingreflection from an object, and the black circles represent directionswhere the received signals have low intensity (e.g., less than theintensity threshold). After the first scan, the radar device/lidardevice generates a saliency map including a first salient region 952 anda second salient region 954. The first salient region 952 is generatedbased on the 4 shaded circles corresponding to the signals reflectedfrom the ball 912, and the second salient region 954 is generated basedon the 8 shaded circles corresponding to the signals reflected from theperson 914. Thus, the saliency map 950 is based on 12 differentdirections, including 4 directions of the 4 shaded circles correspondingto the ball 912 and 8 directions of the 8 shaded circles correspondingto the person 914.

After the saliency map 950 is generated, the radar device/lidar devicemay be configured to receive signals at directions corresponding to thesaliency map 950, where a number of directions corresponding to thesaliency map 950 for the next scan is increased to concentrate thedirections (scan iterations) in the saliency regions. For example, theradar device/lidar device may be configured to receive signals at 16different directions (instead of 4 directions) in the first salientregion 952 and at 32 different directions (instead of 8 differentdirections) in the second salient region 954. Therefore, in the nextscan, the radar device/lidar device obtains the radar/lidar return 970showing signal intensities at 48 different directions, which include 16different directions in the first salient region 952 and at 32 differentdirections in the second salient region 954. In an aspect, the 16different directions in the first salient region may be equally spacedfrom one another, and the 48 different directions in the second salientregion may be equally spaced from one another. As illustrated, a numberof scan iterations per area within the saliency map 950 in the next scan970 is higher than a number of scan iterations per area in the firstscan 930. Because the radar device/lidar device receives signals in moredirections per salient region during the next scan than during the firstscan, the radar device/lidar device receives a higher resolution ofsignal data per salient region in the next scan than the first scan.After several scans based on the saliency map 950, the radardevice/lidar device may perform a reset scan (“dead-reckon”) withoutusing the saliency map 950. The radar device/lidar device may generate anew saliency map based on the reset scan, and then perform subsequentscans based on the new saliency map. The radar device/lidar device mayperform the reset scan every w scans, where w is an integer.

FIG. 10 is a flowchart 1000 of a method of scanning by a scanningdevice, according to an aspect of the disclosure. The method may beperformed by a scanning device for scanning (e.g., the scanning device112, the scanning device 650, the apparatus 1202/1202′). The scanningdevice may be for radio-based scanning and/or laser-based scanning. Inan aspect, the radio-based scanning may include radar scanning and thelaser-based scanning may include lidar scanning. At 1002, the scanningdevice performs a first scan over a target region to obtain a pluralityof first scan samples at a plurality of locations within the targetregion. For example, as discussed supra, as a result of the first scan,the radar device/lidar device obtains the radar/lidar return 830 showingdetected objects as shaded circles and the surrounding regions as blackcircles, where the shaded circles represent directions where thereceived signals have high intensity (e.g., greater than an intensitythreshold) indicating reflection from an object, and the black circlesrepresent directions where the received signals have low intensity(e.g., less than the intensity threshold).

At 1004, the scanning device generates a saliency map of the targetregion based on signal intensities of the plurality of first scansamples. At 1006, the scanning device determines a salient region withinthe target region based on the saliency map. In an aspect, the salientregion is determined based on at least one high intensity area withinthe target region, and the at least one high intensity area correspondsto a location of at least one of the first scan samples with signalintensity greater than an intensity threshold. For example, as discussedsupra, after the first scan, the radar device/lidar device generates asaliency map, where the saliency map has a first salient region 852 anda second salient region 854. For example, as discussed supra, the firstsalient region 852 is generated based on the 4 shaded circlescorresponding to the signals reflected from the ball 812, and the secondsalient region 854 is generated based on the 8 shaded circlescorresponding to the signals reflected from the person 814.

At 1008, the scanning device performs at least one second scan over thesalient region to obtain at least one second scan sample in the salientregion. In an aspect, the scanning device may perform the at least onescan by performing at least one of a high speed scan over the salientregion or a high resolution scan over the salient region. In an aspect,the high speed scan over the salient region may be performed with a samenumber of scan samples per area as a number of scan samples per area forthe first scan over the target region. For example, as discussed supra,according to a first approach, the radar device/lidar device maintains anumber of different directions (scan iterations) that fall within thesaliency map to receive signals. For example, as discussed supra, theradar device/lidar device maintains the resolution for a zone in theregion identified by the saliency map. For example, as discussed supra,after the saliency map 850 is generated, the radar device/lidar deviceis configured to receive signals at directions corresponding to thesaliency map 850. For example, as discussed supra, a number of scaniterations per area within the saliency map 850 in the next scan 870 isthe same as a number of scan iterations per area in the first scan 830.In an aspect, the high resolution scan over the salient region may beperformed with a higher number of scan samples per area than a number ofscan samples per area for the first scan over the target region. Forexample, as discussed supra, the radar device/lidar device may increasea number of different directions (scan iterations) that fall within asaliency map to receive signals. For example, as discussed supra, afterthe saliency map 950 is generated, the radar device/lidar device may beconfigured to receive signals at directions corresponding to thesaliency map 950, where a number of directions corresponding to thesaliency map 950 for the next scan is increased to concentrate thedirections (scan iterations) in the saliency regions. For example, asdiscussed supra, a number of scan iterations per area within thesaliency map 950 in the next scan 970 is higher than a number of scaniterations per area in the first scan 930. At 1010, the scanning devicemay perform additional features, as described infra.

In an aspect, a number of scan samples per area for the first scan and anumber of scan samples per area for the at least one second scan arebased on at least one of a number of receiver elements of the scanningdevice or a scan frequency. For example, as discussed supra, the numberof different directions (scan iterations) may be increased to a numberwhere the angular resolution is high enough to distinguish two adjacentdirections. For example, as discussed supra, the angular resolution ofthe receiver antenna array may be affected by the number of receiverantenna array elements and the radar/lidar scan frequency.

In an aspect, the first scan is performed using beamforming to digitallysteer a direction of the first scan over the target region, and the atleast one second scan is performed using beamforming to digitally steera direction of the at least one second scan over the salient region. Insuch an aspect, the beamforming is performed by adjusting phase valuesfor a plurality of receivers of the scanning device. For example, asdiscussed supra, the DSP aggregates the output from each antenna elementin a way that simulates a large single antenna, by effectively“steering” the receiver antenna array, using a beamforming approach. Forexample, as discussed supra, phase delays may be applied to the receiverantenna elements, such that when the phase-delayed signals from thereceiver antenna elements are added together, the effect of digitalsteering of the receiver antenna array is achieved

FIG. 11 is a flowchart 1100 of a method of scanning by a scanningdevice, expanding from the flowchart 1000 of FIG. 10. The method may beperformed by a scanning device for scanning (e.g., the scanning device112, the scanning device 650, the apparatus 1202/1202′). At 1010, thescanning device continues from the flowchart 1000 of FIG. 10. At 1102,the scanning device performs a reset scan over a second target region toobtain a plurality of reset scan samples at a plurality of locationswithin the second target region when a threshold number of scans havebeen performed over the salient region after the first scan. Forexample, as discussed supra, the radar device/lidar device may perform areset scan after several scans using the saliency map, where the resetscan is performed without using the saliency map. At 1104, the scanningdevice generates an updated saliency map of the second target regionbased on signal intensities of the plurality of reset scan samples. At1106, the scanning device determines an updated salient region based onthe updated saliency map. For example, as discussed supra, a reset scanmay be performed to generate a new saliency map with salient regionsfrom time to time. At 1108, the scanning device performs at least onethird scan over the updated salient region to obtain at least one thirdscan sample in the salient region. For example, as discussed supra, theradar device/lidar device may generate a new saliency map with salientregions based on the reset scan, and then perform subsequent scans basedon the new saliency map and the salient regions.

FIG. 12 is a conceptual data flow diagram 1200 illustrating the dataflow between different means/components in an exemplary apparatus 1202.The apparatus may be a scanning device for radio-based scanning and/orlaser-based scanning. In an aspect, the radio-based scanning may includeradar scanning and the laser-based scanning may include lidar scanning.The apparatus includes a reception component 1204, a transmissioncomponent 1206, a scan management component 1208, and a saliencymanagement component 1210.

The scan management component 1208 performs a first scan (e.g., via thereception component 1204 and the transmission component 1206) over atarget region 1230 to obtain a plurality of first scan samples at aplurality of locations within the target region 1230, at 1252, 1254,1256, and 1258. The scan management component 1208 may determineintensity of the plurality of first scan samples, and may forward theintensity of the plurality of first scan samples to the saliencymanagement component 1210, at 1260. The saliency management component1210 generates a saliency map of the target region based on signalintensities of the plurality of first scan samples. The saliencymanagement component 1210 determines a salient region within the targetregion 1230 based on the saliency map. The saliency management component1210 may forward information about the salient region and the saliencymap to the scan management component 1208, at 1260. The scan managementcomponent 1208 performs at least one second scan (e.g., via thereception component 1204 and the transmission component 1206) over thesalient region to obtain at least one second scan sample in the salientregion within the target region 1230, at 1252, 1254, 1256, and 1258. Inan aspect, the scan management component 1208 may perform the at leastone scan by performing at least one of a high speed scan over thesalient region or a high resolution scan over the salient region. In anaspect, the high speed scan over the salient region may be performedwith a same number of scan samples per area as a number of scan samplesper area for the first scan over the target region 1230. In an aspect,the high resolution scan over the salient region may be performed with ahigher number of scan samples per area than a number of scan samples perarea for the first scan over the target region 1230.

In an aspect, a number of scan samples per area for the first scan and anumber of scan samples per area for the at least one second scan arebased on at least one of a number of receiver elements of the scanningdevice or a scan frequency.

In an aspect, the salient region is determined based on at least onehigh intensity area within the target region 1230, and the at least onehigh intensity area corresponds to a location of at least one of thefirst scan samples with signal intensity greater than an intensitythreshold.

In an aspect, the first scan is performed using beamforming to digitallysteer a direction of the first scan over the target region 1230, and theat least one second scan is performed using beamforming to digitallysteer a direction of the at least one second scan over the salientregion. In such an aspect, the beamforming is performed by adjustingphase values for a plurality of receivers of the scanning device.

In an aspect, the scan management component 1208 performs a reset scan(e.g., via the reception component 1204 and the transmission component1206) over a second target region 1240 to obtain a plurality of resetscan samples at a plurality of locations within the second target region1240 when a threshold number of scans have been performed over thesalient region after the first scan, at 1252, 1254, 1256, and 1258. Thescan management component 1208 may determine intensity of the pluralityof reset scan samples, and may forward the intensity of the plurality ofreset scan samples to the saliency management component 1210, at 1260.The saliency management component 1210 generates an updated saliency mapof the second target region 1240 based on signal intensities of theplurality of reset scan samples. The saliency management component 1210determines an updated salient region based on the updated saliency map.The saliency management component 1210 may forward information about theupdated salient region and the updated saliency map to the scanmanagement component 1208. The scan management component 1208 performsat least one third scan (e.g., via the reception component 1204 and thetransmission component 1206) over the updated salient region to obtainat least one third scan sample in the salient region within the secondtarget region 1240, at 1252, 1254, 1256, and 1258.

The apparatus may include additional components that perform each of theblocks of the algorithm in the aforementioned flowcharts of FIGS. 10 and11. As such, each block in the aforementioned flowcharts of FIGS. 10 and11 may be performed by a component and the apparatus may include one ormore of those components. The components may be one or more hardwarecomponents specifically configured to carry out the statedprocesses/algorithm, implemented by a processor configured to performthe stated processes/algorithm, stored within a computer-readable mediumfor implementation by a processor, or some combination thereof.

FIG. 13 is a diagram 1300 illustrating an example of a hardwareimplementation for an apparatus 1202′ employing a processing system1314. The processing system 1314 may be implemented with a busarchitecture, represented generally by the bus 1324. The bus 1324 mayinclude any number of interconnecting buses and bridges depending on thespecific application of the processing system 1314 and the overalldesign constraints. The bus 1324 links together various circuitsincluding one or more processors and/or hardware components, representedby the processor 1304, the components 1204, 1206, 1208, 1210, and thecomputer-readable medium/memory 1306. The bus 1324 may also link variousother circuits such as timing sources, peripherals, voltage regulators,and power management circuits, which are well known in the art, andtherefore, will not be described any further.

The processing system 1314 may be coupled to a transmitter/receiver1310. The transmitter/receiver 1310 is coupled to one or more antennas1320. The transmitter/receiver 1310 provides a means for transmittingand receiving signals such as wave signals. The transmitter/receiver1310 receives a signal from the one or more antennas 1320, extractsinformation from the received signal, and provides the extractedinformation to the processing system 1314, specifically the receptioncomponent 1204. In addition, the transmitter/receiver 1310 receivesinformation from the processing system 1314, specifically thetransmission component 1206, and based on the received information,generates a signal to be applied to the one or more antennas 1320. Theprocessing system 1314 includes a processor 1304 coupled to acomputer-readable medium/memory 1306. The processor 1304 is responsiblefor general processing, including the execution of software stored onthe computer-readable medium/memory 1306. The software, when executed bythe processor 1304, causes the processing system 1314 to perform thevarious functions described supra for any particular apparatus. Thecomputer-readable medium/memory 1306 may also be used for storing datathat is manipulated by the processor 1304 when executing software. Theprocessing system 1314 further includes at least one of the components1204, 1206, 1208, 1210. The components may be software componentsrunning in the processor 1304, resident/stored in the computer readablemedium/memory 1306, one or more hardware components coupled to theprocessor 1304, or some combination thereof.

In one configuration, the apparatus 1202/1202′ for scanning includesmeans for performing a first scan over a target region to obtain aplurality of first scan samples at a plurality of locations within thetarget region, means for generating a saliency map of the target regionbased on signal intensities of the plurality of first scan samples,means for determining a salient region within the target region based onthe saliency map, and means for performing at least one second scan overthe salient region to obtain at least one second scan sample in thesalient region. In an aspect, the means for performing the at least onesecond scan is configured to perform at least one of a high speed scanover the salient region or a high resolution scan over the salientregion. In an aspect, the apparatus 1202/1202′ includes means forperforming a reset scan over a second target region to obtain aplurality of reset scan samples at a plurality of locations within thesecond target region when a threshold number of scans have beenperformed over the salient region after the first scan, means forgenerating an updated saliency map of the second target region based onsignal intensities of the plurality of reset scan samples, determiningan updated salient region based on the updated saliency map, and meansfor performing at least one third scan over the updated salient regionto obtain at least one third scan sample in the salient region. Theaforementioned means may be one or more of the aforementioned componentsof the apparatus 1202 and/or the processing system 1314 of the apparatus1202′ configured to perform the functions recited by the aforementionedmeans.

It is understood that the specific order or hierarchy of blocks in theprocesses/flowcharts disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of blocks in the processes/flowcharts may berearranged. Further, some blocks may be combined or omitted. Theaccompanying method claims present elements of the various blocks in asample order, and are not meant to be limited to the specific order orhierarchy presented.

The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects. Thus, the claims are not intended to be limited to theaspects shown herein, but is to be accorded the full scope consistentwith the language claims, wherein reference to an element in thesingular is not intended to mean “one and only one” unless specificallyso stated, but rather “one or more.” The word “exemplary” is used hereinto mean “serving as an example, instance, or illustration.” Any aspectdescribed herein as “exemplary” is not necessarily to be construed aspreferred or advantageous over other aspects. Unless specifically statedotherwise, the term “some” refers to one or more. Combinations such as“at least one of A, B, or C,” “one or more of A, B, or C,” “at least oneof A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or anycombination thereof” include any combination of A, B, and/or C, and mayinclude multiples of A, multiples of B, or multiples of C. Specifically,combinations such as “at least one of A, B, or C,” “one or more of A, B,or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and“A, B, C, or any combination thereof” may be A only, B only, C only, Aand B, A and C, B and C, or A and B and C, where any such combinationsmay contain one or more member or members of A, B, or C. All structuraland functional equivalents to the elements of the various aspectsdescribed throughout this disclosure that are known or later come to beknown to those of ordinary skill in the art are expressly incorporatedherein by reference and are intended to be encompassed by the claims.Moreover, nothing disclosed herein is intended to be dedicated to thepublic regardless of whether such disclosure is explicitly recited inthe claims. The words “module,” “mechanism,” “element,” “device,” andthe like may not be a substitute for the word “means.” As such, no claimelement is to be construed as a means plus function unless the elementis expressly recited using the phrase “means for.”

What is claimed is:
 1. A method of scanning by a scanning device,comprising: performing a first scan over a target region to obtain aplurality of first scan samples at a plurality of locations within thetarget region; generating a saliency map of the target region based onsignal intensities of the plurality of first scan samples; determining asalient region within the target region based on the saliency map; andperforming at least one second scan over the salient region to obtain atleast one second scan sample in the salient region.
 2. The method ofclaim 1, wherein the performing the at least one second scan comprises:performing at least one of a high speed scan over the salient region ora high resolution scan over the salient region.
 3. The method of claim2, wherein the high speed scan over the salient region is performed witha same number of scan samples per area as a number of scan samples perarea for the first scan over the target region.
 4. The method of claim2, wherein the high resolution scan over the salient region is performedwith a higher number of scan samples per area than a number of scansamples per area for the first scan over the target region.
 5. Themethod of claim 1, wherein a number of scan samples per area for thefirst scan and a number of scan samples per area for the at least onesecond scan are based on at least one of a number of receiver elementsof the scanning device or a scan frequency.
 6. The method of claim 1,wherein the salient region is determined based on at least one highintensity area within the target region, and wherein the at least onehigh intensity area corresponds to a location of at least one of thefirst scan samples with a signal intensity greater than an intensitythreshold.
 7. The method of claim 1, further comprising: performing areset scan over a second target region to obtain a plurality of resetscan samples at a plurality of locations within the second target regionwhen a threshold number of scans have been performed over the salientregion after the first scan; generating an updated saliency map of thesecond target region based on signal intensities of the plurality ofreset scan samples; determining an updated salient region based on theupdated saliency map; and performing at least one third scan over theupdated salient region to obtain at least one third scan sample in thesalient region.
 8. The method of claim 1, wherein the scanning device isfor at least one of radio-based scanning or laser-based scanning, andwherein the radio-based scanning includes radar scanning and thelaser-based scanning includes lidar scanning.
 9. The method of claim 1,wherein the first scan is performed using beamforming to digitally steera direction of the first scan over the target region, and wherein the atleast one second scan is performed using beamforming to digitally steera direction of the at least one second scan over the salient region. 10.The method of claim 9, wherein the beamforming is performed by adjustingphase values for a plurality of receivers of the scanning device.
 11. Ascanning device for scanning, comprising: means for performing a firstscan over a target region to obtain a plurality of first scan samples ata plurality of locations within the target region; means for generatinga saliency map of the target region based on signal intensities of theplurality of first scan samples; means for determining a salient regionwithin the target region based on the saliency map; and means forperforming at least one second scan over the salient region to obtain atleast one second scan sample in the salient region.
 12. The scanningdevice of claim 11, wherein the means for performing the at least onesecond scan is configured to: perform at least one of a high speed scanover the salient region or a high resolution scan over the salientregion.
 13. The scanning device of claim 12, wherein the high speed scanover the salient region is performed with a same number of scan samplesper area as a number of scan samples per area for the first scan overthe target region.
 14. The scanning device of claim 12, wherein the highresolution scan over the salient region is performed with a highernumber of scan samples per area than a number of scan samples per areafor the first scan over the target region.
 15. The scanning device ofclaim 11, wherein a number of scan samples per area for the first scanand a number of scan samples per area for the at least one second scanare based on at least one of a number of receiver elements of thescanning device or a scan frequency.
 16. The scanning device of claim11, wherein the salient region is determined based on at least one highintensity area within the target region, and wherein the at least onehigh intensity area corresponds to a location of at least one of thefirst scan samples with a signal intensity greater than an intensitythreshold.
 17. The scanning device of claim 11, further comprising:means for performing a reset scan over a second target region to obtaina plurality of reset scan samples at a plurality of locations within thesecond target region when a threshold number of scans have beenperformed over the salient region after the first scan; means forgenerating an updated saliency map of the second target region based onsignal intensities of the plurality of reset scan samples; means fordetermining an updated salient region based on the updated saliency map;and means for performing at least one third scan over the updatedsalient region to obtain at least one third scan sample in the salientregion.
 18. The scanning device of claim 11, wherein the scanning deviceis for at least one of radio-based scanning or laser-based scanning, andwherein the radio-based scanning includes radar scanning and thelaser-based scanning includes lidar scanning.
 19. The scanning device ofclaim 11, wherein the first scan is performed using beamforming todigitally steer a direction of the first scan over the target region,and wherein the at least one second scan is performed using beamformingto digitally steer a direction of the at least one second scan over thesalient region.
 20. The scanning device of claim 19, wherein thebeamforming is performed by adjusting phase values for a plurality ofreceivers of the scanning device.
 21. A scanning device for scanning,comprising: a memory; and at least one processor coupled to the memoryand configured to: perform a first scan over a target region to obtain aplurality of first scan samples at a plurality of locations within thetarget region; generate a saliency map of the target region based onsignal intensities of the plurality of first scan samples; determine asalient region within the target region based on the saliency map; andperform at least one second scan over the salient region to obtain atleast one second scan sample in the salient region.
 22. The scanningdevice of claim 21, wherein the at least one processor configured toperform the at least one second scan is configured to: perform at leastone of a high speed scan over the salient region or a high resolutionscan over the salient region.
 23. The scanning device of claim 22,wherein the high speed scan over the salient region is performed with asame number of scan samples per area as a number of scan samples perarea for the first scan over the target region.
 24. The scanning deviceof claim 22, wherein the high resolution scan over the salient region isperformed with a higher number of scan samples per area than a number ofscan samples per area for the first scan over the target region.
 25. Thescanning device of claim 21, wherein a number of scan samples per areafor the first scan and a number of scan samples per area for the atleast one second scan are based on at least one of a number of receiverelements of the scanning device or a scan frequency.
 26. The scanningdevice of claim 21, wherein the salient region is determined based on atleast one high intensity area within the target region, and wherein theat least one high intensity area corresponds to a location of at leastone of the first scan samples with a signal intensity greater than anintensity threshold.
 27. The scanning device of claim 21, wherein the atleast one processor is further configured to: perform a reset scan overa second target region to obtain a plurality of reset scan samples at aplurality of locations within the second target region when a thresholdnumber of scans have been performed over the salient region after thefirst scan; generate an updated saliency map of the second target regionbased on signal intensities of the plurality of reset scan samples;determine an updated salient region based on the updated saliency map;and perform at least one third scan over the updated salient region toobtain at least one third scan sample in the salient region.
 28. Thescanning device of claim 21, wherein the scanning device is for at leastone of radio-based scanning or laser-based scanning, and wherein theradio-based scanning includes radar scanning and the laser-basedscanning includes lidar scanning.
 29. The scanning device of claim 21,wherein the first scan is performed using beamforming to digitally steera direction of the first scan over the target region, and wherein the atleast one second scan is performed using beamforming to digitally steera direction of the at least one second scan over the salient region. 30.The scanning device of claim 29, wherein the beamforming is performed byadjusting phase values for a plurality of receivers of the scanningdevice.
 31. A computer-readable medium storing computer executable codefor a scanning device for scanning, comprising code to: perform a firstscan over a target region to obtain a plurality of first scan samples ata plurality of locations within the target region; generate a saliencymap of the target region based on signal intensities of the plurality offirst scan samples; determine a salient region within the target regionbased on the saliency map; and perform at least one second scan over thesalient region to obtain at least one second scan sample in the salientregion.
 32. The computer-readable medium of claim 31, wherein the codeto perform the at least one second scan comprises code to: perform atleast one of a high speed scan over the salient region or a highresolution scan over the salient region.
 33. The computer-readablemedium of claim 32, wherein the high speed scan over the salient regionis performed with a same number of scan samples per area as a number ofscan samples per area for the first scan over the target region.
 34. Thecomputer-readable medium of claim 32, wherein the high resolution scanover the salient region is performed with a higher number of scansamples per area than a number of scan samples per area for the firstscan over the target region.
 35. The computer-readable medium of claim31, wherein a number of scan samples per area for the first scan and anumber of scan samples per area for the at least one second scan arebased on at least one of a number of receiver elements of the scanningdevice or a scan frequency.
 36. The computer-readable medium of claim31, wherein the salient region is determined based on at least one highintensity area within the target region, and wherein the at least onehigh intensity area corresponds to a location of at least one of thefirst scan samples with a signal intensity greater than an intensitythreshold.
 37. The computer-readable medium of claim 31, furthercomprises code to: perform a reset scan over a second target region toobtain a plurality of reset scan samples at a plurality of locationswithin the second target region when a threshold number of scans havebeen performed over the salient region after the first scan; generate anupdated saliency map of the second target region based on signalintensities of the plurality of reset scan samples; determine an updatedsalient region based on the updated saliency map; and perform at leastone third scan over the updated salient region to obtain at least onethird scan sample in the salient region.
 38. The computer-readablemedium of claim 31, wherein the scanning device is for at least one ofradio-based scanning or laser-based scanning, and wherein theradio-based scanning includes radar scanning and the laser-basedscanning includes lidar scanning.
 39. The computer-readable medium ofclaim 31, wherein the first scan is performed using beamforming todigitally steer a direction of the first scan over the target region,and wherein the at least one second scan is performed using beamformingto digitally steer a direction of the at least one second scan over thesalient region.
 40. The computer-readable medium of claim 39, whereinthe beamforming is performed by adjusting phase values for a pluralityof receivers of the scanning device.